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D. P. O'Brien, A. Morbidelli (Observatoire de la Cote d'Azur), W. F. Bottke (Southwest Research Institute)
A recent model of the evolution of the outer solar system [1,2] predicts that the outer planets were initially in a much more compact configuration and began to slowly migrate due to interactions with a massive trans-Neptunian disk of planetesimals. After ~700 Myr of slow migration, Jupiter and Saturn cross their mutual 2:1 mean-motion resonance, destabilizing the system, triggering the late heavy bombardment (LHB), and causing a rapid migration of the outer planets to their current orbital configuration. This model requires that the dynamical excitation and resulting collisional activity in the trans-Neptunian disk was low enough that ~35 Earth masses of material could remain after 700 Myr.
We will present the results of simulations of the dynamical excitation of the primordial trans-Neptunian disk and of the resulting collisional evolution of the disk. Our preliminary work suggests that there is a reasonable range of parameters over which the primordial trans-Neptunian disk is able to remain massive (>30 Earth masses) for 700 Myr. In addition, the final size distribution of trans-Neptunian bodies in our simulations is consistent with the survey results of Bernstein et al. [3] for the total trans-Neptunian object (TNO) population. The 700 Myr of collisional evolution in the massive, primordial trans-Neptunian disk would dwarf any subsequent collisional evolution in the current, much less massive TNO population. Hence, the current population of TNOs is likely a fossil remnant of the early primordial phase.
References: [1] Gomes et al., Nature 435, 2005. [2] Tsiganis et al., Nature 435, 2005. [3] Bernstein et al., AJ 128, 2004.
The author(s) of this abstract have provided an email address for comments about the abstract: obrien@obs-nice.fr
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Bulletin of the American Astronomical Society, 37 #3
© 2004. The American Astronomical Soceity.